T-Mobile is currently in the process of pushing a fairly major update to its version of the Galaxy S III, which brings Android 4.1.2 and a slew of new don't-call-it-Touchwiz features.

New Features:

Multi-Window

Auto-pairing via NFC

enhanced Camera options

Sound Balance

Paper Artist

Samsung Gallery

Blocking Mode

Easy Mode

Before grabbing this one, you'll need to be on build T999UVDLJC, have at least 50% battery, and not be rooted. If those bases are covered, you can either elect to pull the 168MB update over-the-air, or, for those who prefer the tethered-to-a-computer method, via Samsung Kies.